The present invention relates to a peptide isolated from the 28 KD protein of S. mansoni, which bears one or more epitopes and to its process of isolation, as well as to monoclonal antibodies adapted to recognize the peptidic antigenic fractions thus isolated and to therapeutic compositions adapted to induce neutralizing anti-body synthesis, which compositions comprise said peptide alone or in association with other suitable substances.
BALLOUL et Al. (MOLECULAR AND BIOCHEMICAL PARASITOLOGY, 17 (1985) p. 105-114) described the synthesis in vitro of an antigen constituted by a polypeptide having a molecular weight of 28 KD and an isoelectric point comprised between 6.3 and 6.8, which constitutes a translation product in vitro of total RNA of Schistosoma mansoni.
The above Authors have pursued their research with the object of isolating from this polypeptide of 28 KD and of identifying, the peptidic epitope or epitopes responsible for the antigenic properties.
It is known to analyze the peptides which constitute proteins isolated from SDS gels, by partial digestion of said proteins by a protease in a buffer containing SDS; stable partial digestion products are obtained, which are composed of numerous peptides whose molecular weights are sufficiently high for it to be possible to separate them on 15% SDS acrylamide gels (CLEVELAND et Al., THE JOURNAL OF BIOLOGICAL CHEMISTRY, 252, p. 1102-1106, (1977)).
Applicants have sought to isolate, from the 28 KD protein of S. mansoni, the one or more peptides bearing the anti-Schistosoma antigenic activity shown by the 28 KD protein, and have made use for this purpose of techniques for isolating peptidic fragments by proteolysis described in the prior art.